<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>悬停按钮</title>
  <style>
    button {
      background-color: #4CAF50; /* Green */
      border: none;
      color: white;
      padding: 16px 32px;
      text-align: center;
      text-decoration: none;
      display: inline-block;
      font-size: 16px;
      margin: 4px 2px;
      transition-duration: 0.4s;
      cursor: pointer;
    }

    .button1 {
      background-color: white;
      color: black;
      border: 2px solid #4CAF50;
    }

    .button1:hover {
      background-color: #4CAF50;
      color: white;
    }

    .button2 {
      background-color: white;
      color: black;
      border: 2px solid #008CBA;
    }

    .button2:hover {
      background-color: #008CBA;
      color: white;
    }

    .button3 {
      background-color: white;
      color: black;
      border: 2px solid #f44336;
    }

    .button3:hover {
      background-color: #f44336;
      color: white;
    }

    .button4 {
      background-color: white;
      color: black;
      border: 2px solid #e7e7e7;
    }

    .button4:hover {background-color: #e7e7e7;}

    .button5 {
      background-color: white;
      color: black;
      border: 2px solid #555555;
    }

    .button5:hover {
      background-color: #555555;
      color: white;
    }
  </style>
</head>
<body>
<button class="button1">绿色</button>
<button class="button2">蓝色</button>
<button class="button3">红色</button>
<button class="button4">灰色</button>
<button class="button5">黑色</button>
</body>
</html>